1. Field of the Invention
The present invention relates to a generation control system that includes a means for calculating an increase in driving torque of a generator that is necessary to stabilize engine rotation speed when an electric load is connected to the generator.
2. Description of the Related Art
If a large electric load is connected to a vehicle ac generator while an engine is running at a lower rotation speed, the driving torque of the ac generator so abruptly increases that the engine may stall due to an excessive amount of torque increase.
JP-A-Hei 6-90532 discloses a generation control system by which field current is gradually increased when an electric load is connected to a generator, thereby preventing engine from stalling.
JP-B2 Hei 7-116960 or its counterpart U.S. Pat. No. 4,877,273 discloses a generation control system by which an engine idling speed is controlled according to current supplied to the electric load and field current when an electric load is connected to a generator.
In the generation control system disclosed in JP-A-Hei 6-90532, an increase in torque to drive the generator due to connection of load is not taken into account. Therefore, time for gradually increasing field current becomes comparatively longer, as indicated by a dotted line in FIG. 5E. Therefore, battery voltage lowers, as shown in FIG. 5B by a dotted line and lamps or other illuminating elements may flicker.
In the generation control system disclosed in JP-B2 Hei 7-116960, a change in the driving torque of the ac generator due to the idling speed and temperature of the ac generator is taken into account when the engine idling speed is controlled to a suitable speed. After the engine idling speed control is started, the engine rotation speed fluctuates as indicated by a dotted line in FIG. 5G This fluctuation may discomfort a driver and a passenger of a vehicle in which an ac generator is mounted.